JPH0557269B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing novel pyridine derivatives having herbicidal properties. According to the present invention, a method for producing a herbicidal pyridine compound represented by the following formula () is provided. {In the formula, Z and Y each represent a chlorine or hydrogen atom, or a trifluoromethyl group, provided that at least one of Z and Y is a trifluoromethyl group, and R ² is (1) carboxamide group

[Formula] [However, R ³ is hydrogen, R ⁴ is a phenyl group or a chlorophenyl group,
or the group -NR ⁵ R ⁶ (R ⁵ is hydrogen and R ⁶ is a phenyl group or chlorophenyl group), or the group -NR ³ R ⁴ in the carboxamide group as R ² is a morpholino group. or R ² (2) group

[Formula] (R ⁷ is a phenyl group), or R ² is (3) a haloalkoxycarbonyl group or (4) a phenoxycarbonyl group (although it may have a halogen or methyl substituent) A herbicidal pyridine compound represented by }. One group of compounds produced by the method of the invention is one in which Z is a _CF3 group, Y is a hydrogen atom,
Including those in which R ² has the same meaning as above. The second of the compounds produced by the method of the present invention
In the group, Z is a _CF3 group, Y is a chlorine atom,
Including those in which R ² has the same meaning as above. The compounds of the invention have asymmetric carbon atoms and can therefore exist in two optically isomeric forms. The invention includes the dextrorotatory and levorotatory isomers of each compound of the invention and mixtures thereof in any proportion. Particular examples of compounds according to the invention include those listed in Table 1 below.

【table】

[Table] For many of the compounds in the above table, physical constants in terms of boiling points or melting points are not available because these compounds are often isolated by thin layer chromatography and a high proportion are viscous oils. . The structures of the compounds were confirmed by testing their nuclear magnetic resonance spectra, which corresponded to the structures specified in Table 1. The compounds prepared by the process of this invention are generally substantially more effective herbicides against grass species than against broadleaf species of plants. They can be used to control undesirable grass species growing singly or, at appropriate application rates, to control weeds growing between broadleaf crop plants. The compound can be applied to the soil before the emergence of undesirable grass species (pre-emergence application) or to the portion of the growing grass plant above the soil (post-emergence application). The compounds produced by the method of the invention can therefore be applied to undesirable plants, especially grass species or to their growing areas, in amounts effective as herbicides of the compounds of formula () as defined above. It can be used in a method of suppressing the growth of these plants. The amount of compound to be applied will depend on a number of factors, such as the particular plant species whose growth is to be inhibited, but 0.025 to 5 Kg/ha is usually suitable;
Preferably it is 0.1-1.0Kg/ha. Those skilled in the art can determine the appropriate amount to use by routine, standardized tests without undue experimentation. The compounds of the invention are preferably applied in the form of compositions, in which the active ingredient is mixed with a carrier consisting of a solid or liquid diluent. Preferably the composition further comprises a surfactant. The solid compositions of the invention may be in the form of powders or granules, for example. Suitable solid diluents include, for example, kaolin, bennite, diatomaceous earth, dolomite, calcium carbonate, talc, powdered magnesia and fuller's earth. The solid compositions may also be in the form of dispersible powders or granules containing, in addition to the active ingredient, wetting agents to facilitate the dispersion of the powder or granules in the liquid. Such powders or granules contain fillers,
This includes prevention of sedimentation, etc. Liquid compositions include aqueous solutions, dispersions and emulsions containing the active ingredient, preferably in the presence of one or more surfactants; Can be used to make emulsions. The liquid compositions of the invention may also contain one or more corrosion inhibitors, such as laurylisoquinolinium bromide. The surfactant may be cationic, anionic or nonionic. Suitable cationic type activators include, for example, quaternary ammonium compounds such as cetyltrimethylammonium bromide.
Suitable anionic active agents are, for example, soaps, salts of aliphatic monoesters of sulfonic acids, such as sodium lauryl sulfonate, and salts of sulfonated aromatic compounds, such as dodecylbenzenesulfonate, sodium lignosulfonate, calcium and ammonium, butylnaphthalene sulfonate and diisopropyl- and triisopropyl-
Contains a mixture of sodium salts of naphthalene sulfonic acid. Suitable nonionic activators include other nonionic activators, including, for example, condensates of ethylene oxide with aliphatic alcohols such as oleyl alcohol and cetyl alcohol or with alkylphenols such as octylphenol, nonylphenol and octylcresol. are partial esters derived from long-chain fatty acids and hexitol anhydride, such as sorbitol monolaurate, condensates of such partial esters with ethylene oxide, and lecithin. Compositions to be used in the form of aqueous solutions, dispersions or emulsions are usually presented in the form of concentrates containing a high proportion of the active ingredient, which concentrates are diluted with water before use. These concentrates usually withstand long periods of storage and, after such storage, require the ability to be diluted with water to produce an aqueous preparation that remains homogeneous long enough to be applied with conventional spray equipment. Ru.
Generally, concentrates are 10-85% by weight, preferably 25-85% by weight.
Advantageously, it contains 65% by weight of active ingredient. Dilute preparations ready for use can contain different amounts of active ingredient depending on the purpose for which they are used, but dilute preparations suitable for many uses contain between 0.01 and 10% by weight, preferably between 0.1 and 1% by weight. % active ingredient by weight. The herbicidal pyridine compound of the formula () produced by the method of the present invention is the herbicidal pyridine compound of the formula () Starting from suitably substituted 2-halogenopyridines represented by (wherein X represents a fluorine, chlorine, bromine or iodine atom, and Y and Z have the same meanings as in () above) It can be manufactured using the following process steps. Three routes are possible for converting this halogenopyridine () into a compound of the invention, and these are described below as routes A, B and C. Route A is summarized in the following reaction equation. Route A (This step corresponds to the method of the invention) In route A, R ¹ , R ² , Z and Y have the meanings already assigned to them and Hal represents a halogen, preferably chlorine or bromine. and M is a cation, such as sodium. In Route A, a suitably substituted halogenopyridine () is reacted with a metal salt of p-methoxyphenol, such as the sodium salt of p-methoxyphenol. The reaction is preferably carried out in a solvent or diluent such as methyl ethyl ketone, tetrahydrofuran, dimethyl sulfoxide or dimethyl acetamide. Thus obtained p
The -methoxyphenoxy compound () is then demethylated to give the corresponding p-hydroxy compound by standard methods, for example by heating with pyridine hydrochloride or with hydrogen bromide in acetic acid. This is then reacted in the form of its metal salt (eg sodium or potassium salt) with a suitable halogenoalkanoic acid derivative () to give the desired compound (). Preferably, this reaction is carried out in a solvent or diluent, such as methyl ethyl ketone. Route B is summarized in the following reaction equation. (This step corresponds to the method of the present invention) According to route B, a suitably substituted 2-halogenopyridine () is reacted with hydroquinone in the presence of a base to form the p- Gives hydroxyphenoxy compound (). The reaction is preferably carried out in a solvent or diluent for the reactants. Examples of suitable solvents include aprotic solvents such as dimethylformamide. The reaction is preferably accelerated by heating to a temperature of, for example, 50-150°C. The base used in the reaction can be, for example, an inorganic base, such as sodium or potassium carbonate. The second stage of route B is the same as the final stage of route A and does not require further explanation. Route C According to Route C, a suitably substituted 2-halogenopyridine () is reacted with a 2-(p-hydroxyphenoxy)propionic acid derivative () in the presence of a base directly to give a compound of the invention. .
The 2-(p-hydroxyphenoxy)propionic acid derivative (2) used here is known per se and can be produced by a conventional method. The reaction is preferably carried out in the presence of a solvent or diluent for the reactants. Examples of solvents include lower ketones such as methyl ethyl ketone. The reaction can be accelerated by heating, for example conveniently carried out at the reflux temperature of the solvent. Examples of bases used in the reaction include inorganic bases such as anhydrous potassium carbonate. The starting material 2-halopyridine compound (2) used here can be prepared by various methods. For example, 5-trifluoromethyl-2-chloropyridine compound () can be prepared by replacing some or all of the chlorine atoms with fluorine atoms by reacting the corresponding 5-trichloromethyl-2-chloropyridine compound with a fluorinating agent. It can be manufactured by 2-chloro-5-trifluoromethylpyridine is thus obtained by reacting 2-chloro-5-trichloromethylpyridine with a fluorinating agent such as antimony trifluoride or liquid hydrogen fluoride. It is believed that some of the chlorinated compounds required as starting materials here are novel compounds. Examples are 2-chloro-5-trichloromethylpyridine and 2,3-dichloro-5-trichloromethylpyridine. In addition to being useful as intermediates for making the compounds of this invention, they have some biological activity as insecticides. When 3-methylpyridine is reacted with chlorine in the liquid phase under the influence of ultraviolet light, 2-chloro-5-trichloromethylpyridine is produced. In this case, 3
- The reaction of methylpyridine (as free base or in salt form) with chlorine is usually carried out in an inert organic solvent. Convenient solvents are halogenated hydrocarbons,
For example, carbon tetrachloride, but other solvents such as hydrocarbons and ethers may also be used, provided they do not react under the conditions of use and produce undesirable by-products in unacceptable amounts. The reaction is slow below room temperature and is conveniently accelerated by heat. Convenient reaction temperatures are, for example, from 50 to 130°C. The solution can be heated under reflux. Preferably, dry reactants and solvents are used. Ultraviolet light may be supplied to the reaction from a suitable electric lamp, or may be dipped into the reaction mixture for best effect. The reaction usually provides a reaction mixture and the desired 2-chloro-5-trichloromethylpyridine can be isolated by conventional methods, such as distillation. In another method for producing 2-halogeno-3- or -5-trifluoromethylpyridine, 2-
Halogeno-3- or -5-carboxypyridine can be reacted with sulfur tetrafluoride in the presence of hydrogen fluoride as shown below for 2-chloro-5-trifluoromethylpyridine. Therefore, according to the gist of the present invention, the following formula () {In the formula, Z and Y each represent a chlorine or hydrogen atom, or a trifluoromethyl group, provided that at least one of Z and Y is a trifluoromethyl group, and R ² is (1) carboxamide group

[Formula] [However, R ³ is hydrogen, R ⁴ is a phenyl group or a chlorophenyl group,
or the group -NR ⁵ R ⁶ (R ⁵ is hydrogen and R ⁶ is a phenyl group or chlorophenyl group), or the group -NR ³ R ⁴ in the carboxamide group as R ² is a morpholino group. ], or R ² is (2) group

[Formula] (R ⁷ is a phenyl group), or R ² is (3) a haloalkoxycarbonyl group or (4) a phenoxycarbonyl group (although it may have a halogen or methyl substituent) } or a metal salt thereof, expressed by the following formula () The following formula (), characterized in that it consists of reacting a compound of [wherein R ² has the above-mentioned meaning and Hal is a halogen] in the presence of a base. [In the formula, R ² , Z and Y have the above meanings]
A method for producing a pyridine compound is provided. The compound of the above formula () is the following formula () It can be produced by a method of demethylating the compound [wherein Z and Y have the meanings shown above]. In addition, the compound of formula () is the compound of formula () shown above. (provided that M is a cation) can be produced by a method of reacting with a compound. Hereinafter, the present invention will be explained with reference to Examples, in which all parts are by weight and all temperatures are by Celsius unless otherwise specified. Example 1 This example demonstrates the preparation of one of the compounds according to the invention, namely phenyl α-(5-trifluoromethyl-2-pyridineoxy)phenoxypropionate (Compound No. 3). . (a) Preparation of 2-chloro-5-trichloromethylpyridine 2-bromo-5- in dry carbon tetrachloride (600 ml)
The hydrochloride salt was obtained by filtration of methylpyridine (55g) and subsequent treatment with dry hydrogen chloride. The precipitated solid was crushed and the mixture was heated to reflux. Dry chlorine was passed through the boiling mixture for 61/2 hours while simultaneously being irradiated by an ultraviolet lamp placed inside the reaction flask. The mixture was then cooled, filtered and evaporated to give a light yellow liquid which solidified on cooling. This was identified as the desired chloro compound by its nuclear magnetic resonance spectrum. (b) Production of 2-chloro-5-trifluoromethylpyridine and 2-chloro-5-difluorochloromethylpyridine 2-chloro-5-trichloromethylpyridine (18g) and antimony trifluoride (50g) were mixed at 140~
Heated at 145°C for 1 hour. The mixture was cooled, mixed with ice and concentrated hydrochloric acid, and extracted with ether. The extracts were washed with water, dried over magnesium sulphate and evaporated. The products from several such preparations were combined and distilled by passing at atmospheric pressure through a short column packed with Fenske rings.
The product boiling between 124-154°C was collected and identified as 2-chloro-5-trifluoromethylpyridine.
The fraction with a higher boiling point was redistilled at a pressure of 20 mmHg to obtain 2-chloro-5-difluorochloromethylpyridine with a boiling point of 82-90°C. (c) Production of 2-p-methoxyphenoxy-5-trifluoromethylpyridine Sodium hydride (50% oil dispersion washed with petroleum, 4.2 g) was dissolved in dry dimethyl sulfoxide (100% oil dispersion, 4.2 g).
ml), stirred in dimethyl sulfoxide (100 ml)
A solution of p-methoxyphenol (10.4 g) dissolved in was added over several minutes. The mixture was stirred for 30 minutes to obtain the sodium salt. A solution of 2-chloro-5-trifluoromethylpyridine (15.0 g) in dimethyl sulfoxide (80 ml) was added to the solution over a period of several minutes. Then heat the mixture to 70-75℃
The mixture was heated for 3 hours and left to cool overnight. Thin layer chromatography revealed that only one compound was present. The mixture was diluted to 1.5 with water and then extracted with ether (3x600ml). The ether extract was washed several times with water, then with 1M sodium hydroxide solution and finally with water (2 x 200ml). The ether extract was dried and evaporated to give the required pyridine compound as a brown oil. (d) Production of 2-p-hydroxyphenoxy-5-trifluoromethylpyridine 2-p-methoxyphenoxy-5-trifluoromethylpyridine (10.5g) was mixed with glacial acetic acid (50ml) and 48% bromide. Stir and heat under reflux in hydrogen acid (50ml) for 71/2 hours. The solution was then evaporated and the remaining oil was treated with sodium bicarbonate solution and shaken with ether (2x300ml). The ether extract was shaken with 2M sodium hydroxide solution (200ml) then water (150ml). The aqueous layer was collected, acidified with 2M hydrochloric acid and extracted with ether (2 x 300ml). By drying and evaporating the ether extract, 2
A brown oil was obtained identified as -p-hydroxyphenoxy-5-trifluoromethylpyridine. (e) Production of Compound No. 3 in Table 1 2-p-hydroxyphenoxy-5-trifluoromethylpyridine (0.22g), α-bromopropionate phenyl ester and potassium carbonate (0.18g) were added to methyl ethyl ketone. (5 ml) in 2
Stir and heat under reflux for an hour. The mixture was allowed to cool overnight, then filtered and the residue was washed with methyl ethyl ketone. The filtrate and washings were evaporated and the remaining oil was subjected to high vacuum to remove traces of solvent. The nuclear magnetic resonance spectrum of the oil was consistent with the designated structure, and the compound was identified as Compound No. 3. Example 2 This example describes the preparation of 2-chloro-5-trichloromethylpyridine by chlorination of 3-methylpyridine under the influence of ultraviolet light. 3-Methylpyridine (10ml) was dissolved in dry carbon tetrachloride (300ml). Heat the solution to reflux (approximately 80
°C), dry chlorine gas was passed through the boiling mixture for 3 hours,
At the same time, it was irradiated from inside with a 100 watt ultraviolet lamp that emits light with a wavelength of 185 nm. When preparative thin layer chromatography (silica, chloroform/cyclohexane) was performed on a sample of the evaporated solution obtained in this way, three main products were obtained with an overall yield of 10-15%. Most of them were identified by nuclear magnetic resonance as the desired 2-chloro-5-trichloromethylpyridine. This was confirmed by mass spectrometry analysis of the resulting solution. The other two major components were 2-chloro-3-trichloromethylpyridine and di(trichloromethyl)pyridine, which were present in 1/2 and 1/3 the amount of the main product, respectively. Example 3 This example illustrates the preparation of 2-chloro-5-trichloromethylpyridine from the salt of 3-methylpyridine. The hydrochloride salt was obtained by treating 3-methylpyridine (15g) with dry HCl gas in dry carbon tetrachloride (200ml). The oil thus obtained was stirred and heated to reflux. Dry chlorine gas was bubbled through the refluxing mixture for 4 hours, during which time it was internally illuminated with the ultraviolet lamp used in Example 1. The reaction mixture was then cooled and separated into a solution and an oily solid by decanting. The latter was purified and found to contain unreacted 3-methylpyridine. Evaporation of the former gave an oily semi-solid which was found by thin layer chromatography to have the characteristics of 2-chloro-5-trichloromethylpyridine. Example 4 This example describes the preparation of 2-chloro-5-trifluoromethylpyridine by an alternative method to Example 1. 6-Chlornicotinic acid (23.6 g), sulfur tetrafluoride (37.4 g) and anhydrous hydrogen fluoride (18.7 g) were heated at 120° C. for 8 hours with stirring in an autoclave. The mixture was cooled, poured onto ice and neutralized with concentrated sodium hydroxide solution at 0°C. The mixture was extracted with ether and the extracts were washed with water, dried and evaporated. The residue was distilled and the fractions at 140-150°C were collected.
Analysis showed that it consisted of 2-chloro-5-trifluoromethylpyridine and some 2-fluoro-5-trifluoromethylpyridine. Example 5 This example describes the preparation of 2-chloro-5-trifluoromethylpyridine by an alternative method to that of Examples 1 and 4. 2-chloro-5-trichloromethylpyridine (30.8 g) and anhydrous hydrogen fluoride (80 g) were heated at 200° C. for 10 hours with stirring in an autoclave.
The mixture was cooled, poured onto ice and neutralized at 0°C. The mixture was filtered and the residue and filtrate were extracted with ether. The ether extract was washed with water, dried and evaporated to give an oil. Distill this and
The fraction boiling at 140-154°C was collected. Analysis showed this to be 2-chloro-5-trifluoromethylpyridine and some 2-fluoro-5-trifluoromethylpyridine. Example 6 (a) Preparation of 2-amino-3-bromo-5-methylpyridine 2-amino-5-methylpyridine (108g) was heated to 90-100°C in glacial acetic acid (300ml) while acetic acid ( Bromine (160g) dissolved in 55ml) was slowly added under stirring. After the addition is complete, add more of the mixture.
Stir and heat for 30 minutes, then cool overnight. The precipitated solid was collected by filtration and mixed with ice, and the mixture was neutralized with concentrated aqueous ammonia while maintaining the temperature at 0-5°C. The solid was collected, washed with water, and dried to obtain a bromine compound. (b) Preparation of 3-bromo-2-chloro-5-methylpyridine The product from (a) (145g) was dissolved in concentrated hydrochloric acid (750ml) and water (450ml) and the solution was cooled to -10°C. Sodium sulfite (54g) dissolved in cold water (450ml)
was added dropwise over a period of 90 minutes with stirring, during which time the mixture was maintained at -5°C. The solution was stirred for a further 2 hours and then basified with concentrated aqueous ammonia, keeping the temperature below 20°C. The precipitated solid was washed with water, dried and dissolved in ether (1500ml).
Washed with cold sodium hydroxide solution (1M, 1). Wash the ether solution twice with water (one each time),
Drying and evaporation gave the desired 3-virome-2-chloro-5-methylpyridine. (c) Production of 2,3-dichloro-5-trichloromethylpyridine
Treated with dry hydrogen chloride in a vacuum. The precipitate was crushed, the suspension was heated to reflux, dry chlorine was bubbled into the mixture and it was illuminated with an ultraviolet lamp. After 41/2 hours, the mixture was cooled, filtered, and the filtrate was evaporated to yield the required 2,3-dichloro-5-trichloromethylpyridine. The mass spectrum was consistent with the structure assigned to this mixture. (d) Preparation of 2,3-dichloro-5-trifluoromethylpyridine The product of (c) (1.0 g) and antimony trifluoride (3.0 g) were heated at 170-180°C for 30 minutes. The mixture was then cooled, mixed with ice and water, and extracted with ether. The ether extract is 2,3-dichloro-
A brown oil was obtained containing a mixture of 5-trifluoromethylpyridine and 3-chloro-2-fluoro-5-trifluoromethylpyridine and a small amount of 2,3-dichloro-3-chlorodifluoromethylpyridine. (e) 3-chloro-2-p-methoxyphenoxy-
Production of 5-trifluoromethylpyridine p-methoxyphenol (1.5 g) was mixed with sodium hydride (a 50% oil dispersion washed with petroleum,
0.6g) was added to the solution in dry dimethyl sulfoxide (30ml) and the mixture was stirred for 15 minutes. A combined solution of the product (1.5 g) obtained from several preparations carried out as described in section (d) in dimethyl sulfoxide (20 ml) was added to the reaction mixture and heated at 60° C. for 4 hours. . Additional sodium hydride (0.3% oily dispersion, washed with petroleum)
g) and potassium carbonate (1.38g) were added. Heating was continued for an additional 4 hours. The mixture was poured onto ice and water and extracted with ether (400ml). Wash the ether extract with water, dilute sodium hydroxide and water;
The product was obtained by drying and evaporating. (f) Production of 3-chloro-2-p-hydroxyphenoxy-5-trifluoromethylpyridine The product of (e) (2 g) was mixed with pyridine hydrochloride (20 g).
and heated at 170-180°C for 6 hours. The mixture was cooled, diluted with dilute hydrochloric acid, and extracted with ether. An oily solid was obtained from the ether extract and purified by preparative thin layer chromatography using silica as an adsorbent and 6% ethanol-chloroform as a solvent. (g) Preparation of Compound No. 9 in Table 1 The product of (f) (0.16 g), α-bromopropionic acid p-chlorophenyl ester and potassium carbonate (0.25 g) were stirred in methyl ethyl ketone (10 ml). The mixture was heated under reflux for 2 hours. The mixture was cooled and filtered. Compound No. 9 was obtained by evaporating the filtrate. 2,3-dichloro-5-trichloromethylpyridine was also produced by an alternative method as follows. (h) Production of 2-amino-3-chloro-5-methylpyridine 2-amino-5-methylpyridine (10.8 g) was kept at 10-15°C in concentrated hydrochloric acid (100 ml), while hydrogen peroxide (30 %, 21 ml) was added dropwise under stirring. After the addition was complete, the mixture was stirred for 11/4 hours without cooling and poured onto ice (approximately 200 g). the mixture,
The pH was adjusted to 8-9 by dropping concentrated ammonia water. During this time, add ice to reduce the temperature to approximately 0℃.
I kept it. The solution was extracted with chloroform (2x300ml). The required chloro compound was obtained as a yellow solid from the chloroform extract. (i) Preparation of 2-bromo3-chloro-5-methylpyridine The product (5.7 g) of section (h) was mixed with hydrobromic acid (48%,
50 ml) was cooled at -15°C to -10°C, and bromine (2.6 ml) was added.
was added dropwise to the solution under stirring. Next, a solution of sodium nitrite (5.53 g) dissolved in water (12 ml) was added dropwise over 45 minutes while maintaining the temperature at -5 to 0°C.
Once the addition was complete, the mixture was stirred for an additional 30 minutes at 0°C and poured onto ice. The mixture was made slightly alkaline by dropwise addition of concentrated aqueous ammonia, while the temperature was maintained at 0° C. by addition of ice. The mixture was extracted with ether (150ml). The ether extracts were washed with water, sodium bisulfite solution and water, then dried and evaporated. The residue was taken up in petroleum (boiling point 40-60°C) and the solution was filtered and evaporated. The residue was identified as 2-bromo-3-chloro-5-methylpyridine. (j) Production of 2,3-dichloro-5-trichloromethylpyridine
This was converted to the hydrochloride salt by treatment with dry hydrogen chloride in ml). Chlorine was passed through the suspension, which was kept at 80°C and illuminated by a UV lamp in the reaction flask. After 3 hours, remove the solvent and 2.
A residue of 3-dichloro-5-trichloromethylpyridine was obtained. Example 7 This example describes the fluorination of 2,3-dichloro-5-trichloromethylpyridine using a fluorinating agent in place of the fluorinating agent of Example 6.
The production of 5-trifluoromethylpyridine is explained. 2,3-Dichloro-5-trichloromethylpyridine (35 g) was heated with anhydrous hydrogen fluoride (100 g) in an autoclave with stirring at 200°C for 10 hours, the cooled reaction mixture was poured onto ice and diluted with water at 0°C. Neutralized with sodium oxide. The mixture was extracted with methylene chloride (750ml). The extracts were washed with water (500ml), sodium carbonate solution (500ml) and water (500ml), dried and evaporated. The remaining oil was evaporated and a fraction boiling 77-83°/25 Torr was collected. This was identified as the desired pyridine derivative. Example 8 This example further demonstrates the preparation of 2,3-dichloro-5-trifluoromethylpyridine. Water was removed by melting antimony trifluoride (61 g) under vacuum. The cooled material was crushed and heated to 65-70°C while antimony pentachloride (6.6g) was added dropwise under stirring. Then 2,3-
Dichloro-5-trichloromethylpyridine (40
g) was added dropwise to the reaction mixture and the whole was heated to 160° C. for 45 minutes. The mixture was cooled and steam distilled.
The distilled oil was extracted with ether (2x
100ml). The ether extract was washed with tartaric acid solution, then water, sodium bicarbonate and water and dried. The residual oil was distilled off. 71~80°／18Torr
The fraction boiling at is identified as the desired pyridine derivative. Example 9 This example describes the preparation of 3-chloro-5-trifluoromethyl-2-p-hydroxyphenoxypyridine by Route B. Dry dimethylformamide (30ml) was degassed by heating at reflux for 30 minutes under a stream of argon.
Hydroquinone (49.5 g) and anhydrous potassium carbonate (6.84 g) were added and heated under reflux for 90 minutes. A solution of 2,3-dichloro-5-trifluoromethylpyridine (6.48 g) in dry, degassed dimethylformamide (30 ml) was added to the above mixture for 4 hours.
It took some time to add. The mixture was cooled overnight and diluted with water (500ml). The mixture was acidified with dilute hydrochloric acid and extracted with ether (2x400ml). The ether extract was washed with water (2 x 500ml) and extracted with dilute sodium hydroxide (300ml). The ether extracts were washed with water and the aqueous fractions were collected and reacidified with hydrochloric acid. The acidified aqueous solution was extracted with chloroform (2 x 400ml). A pale brown oil was obtained from the chloroform extract and triturated with petroleum (boiling point 30-40°C) to give a colorless solid identified as the desired 3-chloro-5-trifluoromethyl-2-p-hydroxyphenoxypyridine. I got it. Example 10 This example describes the preparation of 3-bromo-2-chloro-5-trifluoromethylpyridine. (a) Production of 3-bromo-2-chloro-5-pyridinecarboxylic acid 3-bromo-2-chloro-5-methylpyridine (30 g) was added in water (650 ml) containing potassium permanganate (60 g). The mixture was heated and stirred under reflux for 3 hours. Potassium permanganate (20 g) was then added and the mixture was heated and stirred for an additional 21/2 hours. The unchanged starting material was removed by steam distilling the mixture, filtered hot, and the residue was washed with hot water. The filtrate and washings were cooled and acidified with concentrated hydrochloric acid. The precipitated solid was extracted with ether. The ether extract was dried and evaporated to give 3-bromo-2-chloropyridine-5-carboxylic acid. Ta. (b) Preparation of 3-bromo-2-chloro-5-trifluoromethylpyridine The product of (a) (12 g), sulfur tetrafluoride (20 g) and anhydrous hydrogen fluoride (10 g) were heated in an autoclave for 8 hours.
The mixture was heated and stirred at 120°C for an hour. The product was poured onto ice and neutralized with concentrated sodium hydroxide at 0°C. The mixture was extracted with ether (3x100ml) and the extracts were washed with water, sodium bicarbonate and water. The extract was dried and evaporated to give a brown oil. This was distilled and a boiling fraction of 88-93°C was collected. This was identified as 3-bromo-2-fluoro-5-trifluoromethylpyridine. Example 11 This example describes the preparation of 2,5-dichloro-3-trifluoromethylpyridine and 2,5-dichloro-3-difluoromethylpyridine. (a) Production of 2,5-dichloro-3-trichloromethylpyridine and 2,5-dichloro-3-dichloromethylpyridine 2,5-dichloro-3-methylpyridine (37
g) was treated with sufficient dry hydrogen chloride in dry carbon tetrachloride (500ml) to precipitate the pyridine as the hydrochloride salt. The mixture was then stirred and heated under reflux.
During this period dry chlorine was passed through and the solution was irradiated with an internal UV lamp. Chlorination was continued for 31/2 hours and then the solution was evaporated to give an oily solid. This was washed with petroleum (boiling point 30-40°C). The residue is 2,
It was identified as consisting mainly of 5-dichloro-3-trichloromethylpyridine. By evaporating the filtrate, mainly 2,5-dichloro-3-
An oil was obtained which was identified as consisting of dichloromethylpyridine. (b) Production of 2,5-dichloro-3-trifluoromethylpyridine The 2,5-dichloro-3-trichloromethylpyridine (30g) in (a) above was mixed with anhydrous hydrogen fluoride (90g).
and heated and stirred in an autoclave at 200°C for 10 hours. The contents were cooled, poured into ice and neutralized with concentrated sodium hydroxide at 0°C. The aqueous layer was separated by decanting from the oily organic layer and the latter was extracted several times with methylene chloride (total volume 750 ml). An oil was obtained by drying and evaporating the methylene chloride extract. This was distilled and the fraction boiling at 70-76°C/20 Torr was collected. Analysis shows that this is approximately 10% by weight.
2,5-dichloro-3 containing 5-chloro-2-fluoro-3-trifluoromethylpyridine
-trifluoromethylpyridine. Example 12 This example describes the preparation of 2-chloro-3,5-bis-trifluoromethylpyridine. (a) Preparation of 3,5-bis-trifluoromethylpyridine 3,5-pyridine-dicarboxylic acid (17.5
g) with sulfur tetrafluoride (72 g) and hydrogen fluoride (40 g)
g) in an autoclave at 150-151°C for 8 hours. The cooled reaction mixture was neutralized at 0°C with concentrated aqueous potassium hydroxide solution. The mixture was extracted with methylene chloride and the extracts were dried and evaporated. The residue was distilled and the fraction boiling at 119-128°C was collected. The NMR spectrum showed a mixture of 3,5- and 2,5-bis-trifluoromethylpyridine. (b) Production of 2-chloro-3,5-bis-trifluoromethylpyridine The above compound (3.0 g) was dissolved in dry carbon tetrachloride (250
ml) under reflux while stirring (dry) chlorine slowly into the solution and irradiating the solution with an ultraviolet lamp. After 61/2 hours, the carbon tetrachloride was distilled off and the residue was distilled using a spinning band apparatus.
A fraction boiling between 75 and 85°C was collected and identified as 2-chloro-3,5-bis-trifluoromethylpyridine containing small proportions of 2,5- and 3,5-bis-trifluoropyridine. It was done. Next, the herbicidal efficacy of the pyridine compound of formula () produced by the method of the present invention will be illustrated by test examples. Test Example A This Test Example A shows the herbicidal properties of the compounds of the present invention. 21.8g of each compound
It was formulated for testing by mixing with 5 ml of an emulsion prepared by diluting a solution containing Span 80 and 8.2 g of Tween 20 in methylcyclohexanone to 500 ml with water. Span 80 is a trademark for a surfactant consisting of sorbitan monolaurate.
Tween 20 is a trademark for a surfactant consisting of a condensate of ethylene oxide and sorbitan monooleate in 20 molar proportions. The mixture of compound and emulsion was shaken with glass beads and diluted with 12 ml of water.
diluted to The spray composition thus obtained was applied to young pot plants of the types named in Table 2 below (post-emergence test).
was sprayed at a rate equal to 1000/ha. Damage to plants was evaluated on a scale of 0 to 3 by comparison with untreated plants 14 days after spraying. Here, 0 indicates no effect, and 3 indicates a 75-100% weed killing rate. In the pre-emergence herbicidal activity test, seeds of the test species were placed on the surface of a fiber tray in the soil and the composition
It was sprayed at a rate of /ha. The seeds were then covered with soil. Three weeks after spraying, the seedlings in the sprayed fiber trays were compared to the unsprayed control trays and damage was rated on the same scale of 0-3. The (-) mark in the results table indicates that the test was not conducted. The results are shown in Table 2 below.

[Table] The abbreviations of test plants shown in Table 2 have the following meanings. Lt Lettuce To Tomato 0t/Av Cultivated oats and wild oats (Avena fatua) Wild oats were used for post-emergence tests, and cultivated oats were used for pre-emergence tests. Ll Lolium perenne (perennial rye grass) Cn Cyperus rotundus St Setaria viridis The results in Table 2 clearly demonstrate the selectivity of the herbicidal activity of the compounds of the present invention, and the weed species used in the tests were significantly damaged and , was suppressed, whereas dicots remained essentially undamaged. Test Example B This test example demonstrates the herbicidal properties of yet another compound of the invention. These compounds were tested in the same manner as Test Example A. The results were evaluated and expressed in the same manner. The results are shown in the table below. Please refer to this table as a continuation of Table 2.

【table】

Claims (1)

[Claims] 1. The following general formula () {In the formula, Z and Y each represent a chlorine or hydrogen atom, or a trifluoromethyl group, provided that at least one of Z and Y is a trifluoromethyl group, and R ² is (1) Carboxamide group [Formula] [However, R ³ is hydrogen, R ⁴ is a phenyl group or chlorophenyl group,
or the group -NR ⁵ R ⁶ (R ⁵ is hydrogen and R ⁶ is a phenyl group or chlorophenyl group), or the group -NR ³ R ⁴ in the carboxamide group as R ² is a morpholino group. or R ² represents (2) group [Formula] (R ⁷ is a phenyl group), or R ² represents (3) a haloalkoxycarbonyl group or (4) a phenoxycarbonyl group (However, it may have a halogen or methyl substituent)} In the method for producing a herbicidal pyridine compound represented by the following formula () A compound of [wherein Z and Y have the above-mentioned meanings] or a metal salt thereof is represented by the following formula () The following formula (), characterized in that it consists of reacting a compound of [wherein R ² has the above-mentioned meaning and Hal is a halogen] in the presence of a base. [In the formula, R ² , Z and Y have the above meanings]
A method for producing a pyridine compound.